Mixing device



April 21, 1942.

R. W. SCOTT ETAL MIXING DEVICE Filed March 28, 1-938 2 Sheets-Sheet l INVENTO 7'7- ATTORNEY-9.

Y M Sea 1 DREW O. MCCOLLLH man/ 4 RA /7/v April 1942- r R. w. SCOTT ETAL 2,280,667

MIXING DEVICE Filed March 28, 1938 2 Sheets-Sheet 2 INVENTOR. RAY W $c07'7' 4 Patented Apr. 21, 1942 mxmc DEVICE Bay W. Soottalll Andrew 0; llccollum, Detroit, f

Mich, assignors to Bendix Home Appliances, Inc., South Bend, lnd., a corporation of Delaware Application March :8, 193:, Serial No. 198,431

2 Claims. (Cl. zoo-13a) This invention relates to switches and more particularly to switches suitable for use in devicu for automatically controlling the temperature'oi a mixture of hot and cold liquids.

One of the objects of the invention is to provide a novel snap-acting double contact switch suitablefor use in a temperature controlled water mixing device.

Still mother object of the invention is to provide a mixing device in which the valves are alternately opened and closed under the control of novel snap-acting-mechanism.

, Other objects, advantages and novel features or the invention including novel subcombinations and desirable features will be apparent from the following description of the illustrative embodi- Figure '7 Ban enlarged fragmentary vertical view or the block and spring mechanism oi Figure 4.

The invention is illustrated as an automatic mixing device for hot and cold water particularly adapted for use in connection with an automatic washing machine of the type described and claimed in the United States Patent oi Rex Earl Bassett, Jr. and John W. Chamberlin No. 2,165,884, dated July 11, 1939. As shown in Figure 1 .hot water is supplied through a pipe ll under the control of a valve I! which is normally closed and is opened by a solenoid I4. Cold water is supplied-through a pipe it under the control of a normally closed valve" which is adapted tov be opened by a solenoid 20. The hot and cold water flow intoa common outlet pipe 22 which leads to a mixing chamber 24 from which the mixed hot and cold water is conducted to the washing machine. It will be understood that suitable shut oi! valves are incorporated in the pipes i0 and I to shut oil the supply of water entirely as disclosed in said Patent No. 2,165,884.

The solenoids i4 and 20 are connected to one wire It of a suitable electric circuit and the other wire 2| thereof is connected to a contactor bar 30 through aleai spring 32 which is secured to an insulating plate 34. The contactor bar 30 has a downwardly facing contact at one end and an upwardly racing contact at its other end adapted to engage fixed contacts 36 and 34 respectively which are connected to the solenoids l4 and It. When both contacts are closed as shown in F 8- ure 1, both solenoids will be energized to open valves l2 and II so that a substantially 50-50 mixture or hot and cold water will be discharged through the outlet pipe.

According to the present invention the solenoids are automatically controlled in accordance the temperature of the mixture and for this p rpose a bi-metal strip 40 is secured at one end to. the outlet pipe and lies adjacent and substantially parallel thereto so as to be responsive to the temperature thereof. At its free end the strip 40 carries a knife edge 42 engaging the contactor bar 30 substantially at its center. v

In the normal setting of the device the spring 32 presses down on the left end of the bar 30 and tends to hold it in engagement with the contact 36 and out of engagement with the contact 34. The bi-mefal strip 40 opposes the spring 82 and when the temperature of the outlet pipe is at the desired value, the force asserted by the strip 40 will be just suflicient to raise the bar 30 into engagement-with the contact 38 without disengaging it from the contact 36. If the temperature of the mixed water in the outlet pipe should become too high, the strip 40 will deflect upwardly to raise the right end 01' the bar" out of engagement with the contact 38 thereby de-energizing the solenoid i4 andclosing valve I! to shut oil the hot water. At this time only cold water is flowing through the outlet pipe to cool the mixture in the chamber 24 and as soon as the thermostat 40 has become cooled down in response to the cold water contact 38 will again be closed to open the hot water valve. Similarly it the tempera ure'of the mixture should become too cold, the strip 48 will deflect downwardly permitting the spring 32 to move the bar ll out 01 engagement'with the contact 38 to close the cold water valve. Thus the valves are controlled to produce a mixture at the temperature for which the thermostat 4. is. set. 7

Figures 2 and 3 illustrate a modified thermo stat control including a closed tube adapted to be connected to or inserted in the outlet pipe at any desired point and having a cup-shaped head 48 secured to one end thereof. A shaft 48 is rotatably mounted in the head and extends into the tube where it is secured to one end of a helical bi-metal strip 50. The strip 50 is anchored at one end to a cap 62 on the tube so that it will rotate the shaft 46 in response to temperature changes.

A pair of fixed contacts 54 are secured in a head 46 and connected respectively to the solenoids I4 and 20. Cooperating contacts 66 are carried by one leg of a U-shaped spring 66, the opposite leg of which is secured at its free end to a fixed tap 60 which is connected to one side of .one of the contacts 66 out of engagement with its corresponding contact 64. This interrupts the circuit to one or the other of the solenoids, thereby closing either the cold or the hot water valve in the manner described in connection with Figure l.

The embodiment of Figures 4 to 6 is quite similar to that of Figure 1 and for the sake of brevity of description, parts therein corresponding to like parts in Figure 1 have been designated by the same reference numerals plus 100. In this embodiment the contacts I36 and I 36 are arranged facing each other in spaced relationship and the movable contactor I30 lies between them. As shown, the contactor I30 is supported at one end of a leaf spring I32, the other end of which is fixedly secured to the plate I34. A pair of spaced arms I64 are secured to the contactor I30 to form a yoke lying on opposite sides thereof and the spring I32 has a cut out portion at its center between the arms I64. A block I66 having its opposite edges grooved as best seen in Figure 6 is mounted in the cut out portion of the spring I32 with one of its grooved edges pivotally engaging the spring I32 and its other out out edge engaging an extension I66 on the bi-metal strip I40. The spring I32 is so constructed as to exert a compressive force on the block I66 between its points of engagement with the spring and I with the extension I66.

In this embodiment one of the valves is always closed and the other is always open-so that either hot or cold water is flowing but never both. In the position shown in Figure 4 the strip I40 is moved downwardly in response to a low temperature so that the block I66 has tilted upwardly to the left and moved the contactor I30 into engagement with the contact I36. This energizes the solenoid I4 and admits hot water to the outlet pipe. As the strip I40 rises in response to an increase in temperature, the block I66 will be tilted about its point of engagement with the spring I32 until it passses the dead center position at which time it will snap the contactor I30 downwardly out of engagement with the contact I36 and into engagement with contactor I 36. This action occurs so rapidly that the hot water valve is closed and the cold water valve is opened substantially simultaneously. Cold water will then flow until the parts have cooled down sumciently to cause reversal of the above described operation and this action will continue alternately opening and closing the valves. Since the time required to cool or warm the Darts sumciently to cause a reversal of the valves will depend upon the temperature of the water flowing, it will be apparent that a mixture of hot and cold water at the desired temperature will be obtained in the mixing chamber 24.

While the invention has been particularly described in connection with a water mixing device for use in automatic washing machines. it will be apparent that it might be utilized for any other purpose and that structural changes might be made therein. It is accordingly not intended to limit the scope of the invention to the forms shown nor otherwise than by the terms of the appended claims.

What is claimed is:

1. A thermostatic switch comprising spaced contacts, a movable contactor engageable with either of-said contacts, said movable contactor including a pair of spaced legs forming a yoke, a bimetal strip secured at one end to an element, the temperature of which is to be controlled, and a block lying within and held in place by said yoke and pivotally engaging the contactor and the other end of the bimetal strip and forming a snap-acting connection therebetween.

2. A thermostatic switch comprising spaced contacts, a movable contactor engageable with either of said contacts, said movable contactor including a pair of spaced legs forming a yoke, a leaf spring carrying said contactor at one end and fixedly secured at.the other, a bimetal strip secured at one end to an element the temperatureoi which is to be controlled, and a block pivotally engaging the contactor and the other end of the bimetal strip and forming a snap-acting connection therebetween, said block being held in place by the tension of the leaf spring.

RAY W. SCO'I'I.

ANDREW O. McCOLLUM. 

